Transcutaneous electrical nerve stimulation (TENS) is an alternative treatment for muscle soreness and muscle pain to massage.
Most currently available TENS apparatuses, such as one disclosed in Taiwanese Patent No. M488321, are designed based on theories of western medicine, and the intensity and frequency of the stimulation outputted thereby are user adjustable. Stimulation with low frequency (e.g., <10 Hz) current could enhance secretion of Endorphin and alleviate the feeling of pain. Stimulation with higher frequency (e.g., >100 Hz) current could block transmission of pain signals by inducing pre-synaptic inhibition on thick and thin afferent nerve fibers which form synapses with transmission cells, so that the pain is suppressed. In practice, composite electrical stimulation, where currents of different frequencies are alternately outputted, is commonly used to relieve pain.
From the perspective of traditional Chinese medicine, pain results from blood stasis, a phenomenon in which circulation of qi and blood is inhibited inside the meridians. If not uninhibited in time, the inhibited qi and blood may eventually form poison and result in pain and discomfort. Therefore, facilitating the circulation of qi and blood in the meridians would relieve or eliminate the pain and feelings of discomfort.